<!DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<head><title>兴趣小组</title></head>
<body>
<canvas id="canvas"></canvas>
<style type="text/css">
    body {
        margin: 0;
        padding: 0;
        overflow: hidden;
    }
</style>
<script type="text/javascript">
    var canvas = document.getElementById('canvas');
    var ctx = canvas.getContext('2d');


    canvas.height = window.innerHeight;
    canvas.width = window.innerWidth;

    var texts = '阿喆最帅'.split('');

    var fontSize = 16;
    var columns = canvas.width / fontSize;
    // 用于计算输出文字时坐标，所以长度即为列数
    var drops = [];
    //初始值
    for (var x = 0; x < columns; x++) {
        drops[x] = 1;
    }

    function draw() {
        //让背景逐渐由透明到不透明
        ctx.fillStyle = 'rgba(0, 0, 0, 0.05)';
        ctx.fillRect(0, 0, canvas.width, canvas.height);
        //文字颜色
        ctx.fillStyle = '#0F0';
        ctx.font = fontSize + 'px arial';
        //逐行输出文字
        for (var i = 0; i < drops.length; i++) {
            var text = texts[Math.floor(Math.random() * texts.length)];
            ctx.fillText(text, i * fontSize, drops[i] * fontSize);

            if (drops[i] * fontSize > canvas.height || Math.random() > 0.95) {
                drops[i] = 0;
            }

            drops[i]++;
        }
    }

    setInterval(draw, 33);
</script>
</body>
